A series of carefully selected alloys representative of the copper-aluminum (aluminum bronze) base compositions currently being used to an increasing extent in dentistry will be evaluated. This investigation will include two aluminum bronze alloys, a hybrid aluminum bronze-brass alloy, a beta brass (high zinc) alloy as a negative control, and two gold alloys as positive controls. It is hypothesized that the aluminum bronze alloys undergo considerable in vivo biodegradation and may result in epidemiologically significant problems. The study to test this hypotheses will be divided into two major phases. In Phase I a series of laboratory and animal investigations will be conducted to evaluate the efficacy of Cu-base alloys for clinical use. If the results in Phase I indicate that these alloys are acceptable for clinical restorations then a controlled clinical study will be conducted in years 3-5. It is proposed that the decision to conduct the clinical study will be made in collaboration with the NIDR study section. In Phase I, each alloy and appropriate controls will be investigated metallurgically and mechanically to determine characteristics relating to casting, heat treatment, and microstructure. In vitro electrochemical corrosion analyses will be conducted in simulated physiological environments to establish basic mechanisms of corrosion for each alloy system. Additionally, the biocompatibility of each alloy will be evaluated with a series of standard ADA and ASTM tissue culture analyses and laboratory animal investigations to establish quantitative relationships between basic biodegradation phenomena, local tissue and systemic host responses. The basic metallurgical and corrosion properties will be cross correlated with various standardized ADA and ASTM biocompatibility tests currently being used to accept or reject alloy systems. The final stage of the proposed investigation calls for controlled human clinical trials if the biocompatibility and other results justify the use of these alloys, as determined by peer review. This study should generate both fundamental and applied information on the copper-base alloys currently being used as replacements for dental gold alloys. This information will provide critical clinical evaluations for direct correlations with basic characterization and corrosion data so that alloy optimization and clinical longivities will be enhanced. These results should provide opportunities for improved health care in dentistry.